IMO, there's no better or worse when it comes to grip. It's all about what the individual likes(even if it's just to look cool) and feels comfortable with.
Traditional grip was created to suit the ergonomics(is that the word?) of the old marching snares. So technically, you can play the drums using any grip, as long as you don't hurt yourself. You just have to practice. If the old marching snares tilted at a different angle, or were higher up, the "traditional" grip they invented would not be the "traditional" grip we know of now.
To answer to TS's question/problem, just practice very slowly, and take your time. It's about control and accuracy, not speed. Practice doubles/singles at a low tempo(semiquavers at 40bpm) and make sure you are relaxed and get the correct technique down cleanly.
Also, watch Dave Weckl's videos on youtube on hand technique(It's called A natural evolution-developing technique or something like that. There are 3 parts). They're really helpful.